A 71-year-old man was decapitated in Petone on Friday evening.
Police confirmed the horrific act in a statement released on Monday afternoon, and say that they expect to be able to formally name the deceased on Tuesday.
They are currently examining the scene at Jackson St, and are expecting that the investigation will continue over several days.
A witness spoke to Stuff about the incident, saying that the victim's head was wrapped in plastic bag and thrown out of a second-storey window in front of several children.
Police have not confirmed this.
Police also will not speculate on the motive for the killing.
One man was arrested on Friday evening on unrelated charges of wilful damage and drug possession. Police have now clarified that neither he, nor the victim, have any gang affiliations.
Police are asking for anyone who may have any information to call Wellington Police on (04) 381 2000, or anonymously contact Crimestoppers on 0800 555 111.